Ran across these on the web - was wondering if anyone has any practical experience with them. They make an interesting argument for their product, and they appear to be accepable for ponds & lakes with fairly calm water. (Although they do show a video using one in the surf as well). Anyone?

Although the videos show it being very stable, I think all demo videos show greater stability than the average user would achieve. For example Native kayaks (it really is a canoe did not seem nearly as stable when I tried it, but I am sure practice would improve the results).

I have no experience with or have ever seen a kayak that looks like the Wavewalker; I wonder if that means something.

It would appear to be a very slow kayak; and therefore, your need for range would be an important consideration. It also appears that a wave or a hard rain could fill the cockpit, and then you would have to pump it out. During a kayak fishing contest on Lake Lanier in north GA, a Native kayak had to towed in by a Hobie during a hard rain. You cannot make any speed with a kayak that is full of water - even if it will not sink.

FWIW, I have a Hobie Mirage. If you put the pontoon kit on it, it would be stable enough to stand in. The Mirage drive gives you about 3 mph with minimal effort (about like riding a bike at 8 mph).